In your grid there is an XY-wing 59-58-89. Extending the 59 pincer by grouped coloring to R8C9 eliminates 9 in R8C4.

(Which is how I originally solved it.)

Hello Keith,

I normally check the puzzles posted in this group, but I try to only post unusual solutions that catch my eye ... or answer questions that may be raised. That way, I'm hoping not to interfere with the well-earned solutions like you and others post.

Regards, Danny

FWIW: There's a <15> gM-Wing present in the first four cells of my chain.

strong link on 1's in row 8 join the (14) cell in r3c9 and the (13) cell in r2c2,
much like how a w-wing joins two bi-value cells, except obviously these cells aren't identical. so you would need one more link to provide the pincer 4 in this case.